Punch press



Aug. 1946.

H. B. WERNER ET AL PUNCH PRESS Filed March 19, 19 .3 5 Sheets-Sheet l Aug. 6, 1946. H. B. WERNER ET AL A PUNCH PRESS Filed March 19, 1943 5-Sheets-Sheet 2 #9.. ibltr Ja E- Pg Aug. 6, 1946. H. B. 'WERNER ET AL I PUNCH PRESS Filed March 19, 1943 5 Sheets-Sheet. 2?

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PUNCH PRESS Filed March 19, 1943 5 Sheets-Sheet 5 Patented Aug. 6, 1946 UNITED STATE PUNCH PRESS Herbert B. Werner and John Verson, Chicago, 111., assignors to Verson Allsteel Press Company, Chicago, 111., a corporation of Delaware Application March 19, 1943, Serial No. 479,694

14 Claims.

l'he present invention relates to punch presses,

and is more particularly concerned with the provision of a metal drawing press of novel construction having a combination of advantageous features not heretofore found in any one type of press.

Punch presses or metal drawing presses as heretofore constructed have usually been either of the mechanical type or of the hydraulic type. Each of these types of presses ha well known advantages and disadvantages, and in general the choosing of a particular type of press-miechanical or hydraulice-i governed largely by whether the advantages more than compensate for the disadvantages of that type in the par ticular operation to be performed. For a'better understanding of the present invention, the generally admitted advantages and disadvantages of mechanical and hydraulic presses are given below.

A mechanical press usually comprises an electric motor which rotate a heavy flywheel, this rotating flywheel being periodically connected by means of a clutch to a crankshaft or eccentric shaft which drives the slide whenever the clutch is engaged. With this construction, therefore, a large amount of energy can be stored inthe flywheel which runs continuously. Thus, whenever the crank is connected to the flywheel the energy necessary for driving the crank comes partially from the electric motor, but largely from the inertia of the flywheel. Therefore, if desired, a momentary high tonnage well in excess of the pres rated capacity can be reached. Another important advantage i that if the press operation requires the use of a comparatively long slide, two cranks and two connecting rods can be used for driving the slide, it being quite simple to apply pressure from the two connecting rods evenly so as to move the slide downwardly always in a position parallel to the bed even though the die load may be unequally distributed upon the slide.

One of the important disadvantages of the mechanical press is that the slide does not move at a constant velocity, its maximum velocity being attained at approximately the mid-point in the stroke, while at the bottom of the stroke the velocity is substantially zero. This well known to be a decided disadvantage in drawing metals. The tonnage which can be exerted by the slide i of course the reverse; that is, the press exerts the least tonnage at the mid-point in its stroke, and the maximum tonnage at the lower end of its stroke. ()ne effect of this is that if he dies are improperly adjusted, they may come solidly together before the slide has reached its lowermost position at a point in the press stroke where the tonnage exerted by the slide is theoretically almost infinite. It is apparent, therefore, that some element of a mechanical punch press will almost certainly be broken if the two dies come solidly together just before the slide reaches the lowest point in its stroke. Yet another disadvantage of mechanical presses is that they must be designed for some certain troke, and therefore work which permits the use of a shorter stroke nevertheless requires that the press go through a complete time consuming cycle even though during the major portion of the cycle the press is accomplishing no useful function.

One of the most desirable features of a hydraulic press is that it is comparatively easy to obtain a uniform speed of slide movement, which is well known to be desirable in drawing metals. Further, a hydraulic press will carry its rated tonnage through the full stroke of its draw period, which as has been explained, is impossible in a mechanical press since the tonnage which can be exerted by the slide varies, depending upon the angle between the crank arm and the connecting rod. Another advantage of the hydraulic presses is that such presses can be easily made in such a manner that the stroke of the slide can be adjusted to suit the 'work at hand. For instance. a hydraulic press designed for a 24-inch stroke can be adjusted to work at a 10-inch stroke. thereby greatly increasing the number of working cycles during any particular time interval.

Hydraulic presses constructed a few years ago were frequently of the accumulator type, in which fluid under pressure is accumulated within a reservoir, the reservoir being connected to the press cylinder whenever movement of the press slide is desired. Such an accumulator system, in addition to the danger present when large reservoirs are filled with fluid under high pressure, also has the disadvantage that the flow of fluid to the press cylinder from the accumulator reservoir must be throttled, as otherwise the slide will move at extremely high velocity. This throttling was usually accomplished by means of valves, which greatly reduced the eiliciency of the press since they absorbed considerable energy. Presses of the accumulator type for this and other reasons therefore have not received favorable attention in recent years because of the development of mod cm high speed hydraulic press pumps.

Hydraulic presses using high speed pumps cause fluid under pressure to flow directly from the pumps to the press cylinder, the speed of movement of the slide being largely controlled by the volumetric output of the pump. Th reciprocating plungers in high speed pumps of this type cause shearing of the oil film, which raises the temperature of the oil considerably. As the viscosity of the oil depends quite largely upon its temperature, elaborate and expensive cooling system must be employed to dissipate the heat generated by the high speed pumps. If the tempera ture of the oil is not controlled, the oil will thin out and cause the pump to operate at very low efliciency.

Inasmuch as the horsepower of the motor which drives the pump must at least equal the horsepower output of the pump, hydraulic systems of this type having no provision for storing energy such as in a flywheel, a hydraulic press cannot operate at peak loads which require more power than is available in the motor. For this reason the horsepower output of the electric motor for driving a hydraulic press usually must be about three times that necessary to drive a mechanical press of equal tonnage rating.

Another disadvantage of hydraulic presses is that when a comparatively wide slide is used, it is notpractical to use two cylinders for driving the slide if there is the possibility of encountering an eccentric load, and such loads are not at all unusual. As an example, suppose a hydraulic press having two cylinders working side by side, suppose further that the slide in such a press meets an eccentric load, thereby imposing a greater load upon one cylinder than the other.

The effect is that the two hydraulic cylinders will continue to exert the same force, and the slide will therefore be tilted, causing it to bind and also causing an uneven approach of the dies. In fact, if the eccentricity of the load is considerable, the press will most certainly be wrecked, since no press frame can endure such wracking.

With the above advantages and disadvantages of mechanical and hydraulic presses in mind, it is the purpose of the present invention to provide a press having the combined advantages of mechanical presses and hydraulic presses without their accompanying disadvantages.

Yet another object of the present invention is to provide a novel press combining the desirable qualities of both mechanical and hydraulic presses.

A further object of the present invention is to provide a novel metal working press having the following features:

Momentary high pressures beyond the normal capacity of the press are obtainable;

The slide can move at a uniform velocity during the drawing portion of the cycle;

A rapid approach to the work is provided, as is a rapid return, together with adequate stripping force;

The press exerts a constant force throughout the entire draw period;

The length of stroke is easily adjustable;

Power can be stored in a flywheel so as to take care of peak loads beyond the capacity of the prime mover used to energize the press;

Long slides can be used in conjunction with multiple slide cylinders without eccentric loads causing wracking of the press;

High coining pressures can be obtained at the bottom of the stroke;

Safety arrangements can be easily incorporated to return the slide whenever the tonnage approaches an unsafe level;

No high speed piston are used, and therefore the oil is not heated, thereby dispensing with the need of an elaborate cooling system;

' If desired, water may be used as the hydraulic fluid rather than oil, with the result that small leaks do not cause an accumulation of messy oil pools; and

a The initial investment necessary to supply oil is not required.

Other objects and advantages will become ap- '4 parent from the following description of a preferred embodiment of our invention illustrated in the accompanying drawings, in which similar characters of reference to similar parts throughout the several views.

In the drawings,

Fig. 1 is a front elevation of a metal drawing press incorporating the present invention, a portion of the crown being broken away to illustrate one of the press cylinders in vertical section;

Fig, 2 is a side elevation of the press illustrated in Fig. 1, a portion of the gear housing being illustrated in vertical section better to disclose the gear train;

Fig. 3 is a sectional view taken in the direction of the arrows substantially along the line 3-3 of Fig. 2;

Fig. 4 is a fractional vertical sectional view taken in the direction of the arrows along the line 4-4 of Fig. 3;

Fig, 5 is a fractional view illustrating a portion of the hydraulic drive mechanism in the position it assumes when at rest before the beginning of a press stroke;

Fig. 6 is a sectional view of a holding valve used in the press illustrated in the before mentioned figures; and

Fig. 7 is a schematic view of the right side of the press of Fig. 1 showing the hydraulic and control circuits.

In the drawings the punch press frame is indicated generally by the numeral l0. At the lower portion of this frame a bed i2 is secured to side members M, the upper ends of the side members being connected to a crown IS. A slide i3 is located between the side members 14- and reciprocates in guides 20. The punch press dies, not shown, are arranged with the lower die element resting upon a bolster plate 22 secured to the bed I2, while the upper die element is secured to the lower face of the slide [8.

The upper surface of the slide 18 is connected to the lower ends of a pair of piston rods, the lefthand rod in Fig. 1 being indicated by the numeral 24, while the righthand rod is numbered 26. These rods are provided at their upper ends with pistons 28 and 30, respectively, which reciprocate in cylinders 32 and 3%, respectively,

The piston rods 24 and 26 are somewhat smaller in diameter than the pistons 28 and 30 and pass through packing glands 36 arranged at the lower ends of the cylinders. Thus, any given quantity of fluid forced into the upper portions of the cylinders will produce a less displacement of the pistons and rods than will the same volume of fluid when forced into the lower portions of the cylinders.

The drive system for the press comprises an electric motor 38 connected by a plurality of belts so to a flywheel 42. This fly wheel is journaled to rotate upon a shaft 44 extending transversely of the press, the ends of the shaft being journaled in the sides of the crown IS. A clutch 46 of any suitable type such as that shown in United States Letters Patent No 2,286,943, is seured to the shaft 44 and is adapted when engaged to connect the flywheel 42 to drive the shaft 45. Therefore, whenever the clutch 46 is disengaged the motor 38 drives the flywheel 42 at a comparatively uniform velocity. Whenever the clutch 46, is engaged, the shaft 44 rotates at flywheel speed, the energy stored in the flywheel being transferred to this shaft.

Inasmuch as the arrangement of the mechanism at one side of the press is substantially the reverse complement of the mechanism at the other side, only that the righthand side of the press will be described in detail, similar numbers being applied to similar elements at the lefthand side.

Each end of the shaft 44 is keyed to a pinion 48 which meshes with a larger gear 59 keyed to a short gear shaft 52. This shaft 52 in turn is provided with a pinion M which drives a larger gear 56 keyed to a shaft 58. The gear 56 is in turn meshed with another gear 60 of identical size mounted upon a shaft 62 substantially identical to the shaft 58, it being understood that the shafts 52, 58 62 are uitably journaled in the press crown in bearing sleeves 64. When the clutch 45 is engaged so that the flywheel a2 rotates the shaft M, it is apparent that this drive, being communicated from the pinion 48 to the gear 59, from the pinion 54 to the gear 56, and from the gear 56 to the gear 60, will drive the shafts 58 and 62 at reduced speed and in opposite directions.

The shafts 58 and 62 are spaced on opposite sides of a pressure cylinder 66, to be described presently, and are provided with pinions 68 and M, respectively. These pinions 68 and it are meshed with vertically extending racks I2 and M which are secured to the sides of the pressure cylinder 65, so that when the clutch at is engaged with the flywheel 42 rotating, the racks i2 and I4 and the pressure cylinder 68 will be driven downwardly.

The pressure cylinder 55, although it may be of any suitable length depending upon the particular press, is in the present embodiment of the invention shown as being approximately half the height of the press in length. This pressure cylinder is closed at its upper end by a cap .16 which may be welded or otherwise suitably secured in place. The pressure cylinder telescopes over a tube I8 having a length slightly less than that of the pressure cylinder. At its lower end the pressure cylinder is equipped with a sleeve 89 in sliding contact with the tube '18, while just beneath this sleeve the cylinder is hydraulically sealed to the sleeve by a packing gland 82.

The lower end of the tube '53 is welded or otherwise suitably secured to a tubular fitting 8% which passes through a support plate 86 located in the base of the press. The fitting B5 is provided with a shoulder 83 which rests against the upper surface of the plate 86 and is held rigidly in place by a nut 93 threaded to the fitting 84 in a position beneath the plate 86.

When the press is at rest with the slide in its uppermost position, the lower end of the cylinder 66 is slightly below the pinions $3 and I9 (Fig. 5). These pinions therefore mesh with the lower portions of the racks l2 and is, the racks and cylinder extending upwardly into a position somewhat above the press crown. When the cylinder 55 is in its lowermost position, the lower end of the cylinder is brought to a position near the lower end of the tube 178, the upper ends of the racks l2 and 54 then being located somewhat above the pinions 68 and In (Fig. 4.). As has been previously mentioned, the mechanism just described located at the righthand side of the press is duplicated by smilar mechanism at the lefthand side.

The fittings it at the lower end of the tubes i8 are connected to hydraulic conduits, the one to the right being indicated by the numeral 92 while the similar pipe connected to the lefthand tube is indicated by the numeral 94. The pipe 92 is connected through a checkvalve 96 to a hydraulic storage receptacle 98. The check valve 96 is so positioned in the line as to permit flow of fluid from the receptacle 98 downwardly into the pipe 92 but to prevent flow in the reverse direction. Between the tube I8 and the check valve 96 the pipe 92 is connected to an opening A in a 4-way valve 109, shown schematically in Fig. 7. Another opening B of this valve is connected to a pipe I92 leading to the pipe connecting the storage receptacle 9!! with the check valve 96 so that there is free communication between the receptacle 98 the opening B in the valve I at all times. A third opening C in the 4-way valve I99 is connected by a pipe I94 with the space in the cylinder above the piston 39. A fourth opening I) of the valve E99 is connected by a pipe I515 to the inlet opening of a holding valve H38, this valve being illustrated in greater detail in 5. Still another pipe H9 connects the space in the cylinder 3% beneath the piston 30 with the outlet side of the holding valve I08.

Referring to f ig. 6, it will be seen that the holding valve I98 comprises a valve body having a lower chamber I I2 and an upper chamber H4. The lower chamber has a side port leading to the pipe I06, and a valve seat IIB communicating with the pipe III]. A conical valve H8 is located within the chamber I I2 and prevents communication between the pipes IE6 and I I9 whenever it is pressed against the seat H6. This valve H9 is connected by means of a stem I29 with a piston I22 located in the upper chamber H4. A coil spring 25 is located above the piston I22 and biases the piston I22 and valve IIB downwardly, the space above the piston I22 being vented to the atmosphere through a port I26 in a cap I28 which closes the upper end of the chamber H4. The lower portion of this chamber IM, that is, the portion below the piston I22, communicates through a fitting Ito with an air pipe I32, the air pipe being in turn connected to the upper portion of the storage receptacle 98 through an air valve I36.

The valve Inn is of a standard type and comprises a housing :66 in which slides a shiftable spool M8 having a pair of pistons I59, I52 thereon; the spool MS is bored at I54 to provide communication between the outer faces of the pistons I553, 552. The spool is connected to a piston I56 slidable in an air cylinder I58 which is in communication with the 269 pounds per square inch air pressure source through conduit I69 controlled by a solenoid operated valve I62. The piston I56 is biased against the air pressure by a spring I53. When in one positionthe rest and return position-the valve will connects the opening A with the opening D and the opening B with the opening 0', when in the other position-the pressing position-the valve connects the opening A with the opening C, and the opening B with the opening D.

The air valve I 34 (Fig. 7) may be of the solenoid operated type, and in one position it vents the pipe !32 to the atmosphere through port I54 in valve body use and port I 58. In the other position it connects the pipe 932 to the reservoir through the ducts I68 and I79 in the valve housing.

The piping and valves just described connected to the cylinder at, the receptacle 98, and pipe 92, are duplicated on the opposite side of the press, this lefthand piping connecting the pipe 94, the cylinder 32 and the receptacle 98. An air pipe I 35 leading to any suitable source of pneumatic pressure is connected to the upper portion of the receptacle 98 and is used to maintain this receptacle under a suitable comparatively constant pressure, for example a pressure of approximately 260 pounds per square inch.

The operation of the press will be described primarily with reference to Figs. 1 and 7.

The above described press operates in the following manner: When at rest, the receptacle 98 is partially full of hydraulic fiuid, the remaining portion being filled with air at approximately 200 pounds per square inch pressure through the pipe I35. This pneumatic pressure of 200 pounds per square inch is also communicated to the air valves I34, I92, and I12 (the latter valve con trolling the operation of the clutch 46) but when the press is at rest these valves are closed and thus no air under pressure reaches the chamber H4 beneath the piston I22 in the valves I99 or the cylinder H8 in the valve I90. The springs I24 therefore urge the valves I58 into their seats so as to prevent communication between the pipes H and the pipes I05. Hydraulic fluid in the cylinders 32 and 34 beneath the pistons therefore cannot escape through the pipes H9, and thus the slide is maintained in its upper position by the valves I08 even though the pneumatic pressure may fail.

When the press is at rest, the spool of the valve I 00 is so positioned that the opening A is connected to the opening D, while the opening C is connected to the opening B. The pressure of 200 pounds per square inch therefore is communicated through the check valve 95 and pipe 92 to the opening A and thence to the opening D, while similarly this same pressure is communicated through the pipe I92 to the pipe I94 since openings B and C are connected in the valve I90. The pressure in the upper portion of the cylinder 34 is therefore 200 pounds per square inch.

To condition the press for operation, the motor 38 is energized so as to bring the flywheel 42 up to speed. The press cycle is then started by pressing button I'I4 to close switches I70, I18, and I89, which are connected to the source of electrical power I92, I84 through suitable circuits to be hereinafter described. Closing switch Iii: energizes the solenoid controlling valve I 52 to close holding circuit Hit through conductor I88, switch I9Ii, solenoid conductor I92, normally closed switch I42 and conductor I95 to the line I84, and to connect the cylinder I58 with the top of the reservoir 98 to shift the spool I49 to pressing position.

Closing switches I10 and I89, energize the solenoid controlling the valve I34 to close the holding circuit I98 through conductor I88, conductor 200, switch 292, solenoid conductor 294, switch I 80 and conductor 206 to line I84, and to connect the chamber H4 below the piston I22 with the top of the reservoir 98 to open the valve I94.

After the slide I8 has started to descend toward the press bed, upper position limit switch I44 closes, The terminals of limit switch I44 are in parallel with the terminals of switch I80 so that the operator can release the start button Il4 as soon as the slide I8 starts its descent.

The immediate effect of shifting the air valve I94 to such position that the air line is connected to the pipe I32, is to place the chamber II4 under a pressure of 200 pounds per square inch. This pressure opposes the spring I24 and the 200 pounds per square inch pressure in the chamber H2 and lifts the piston I22, thereby raising the valve I I8 from its seat so as to permit communication between the pipes I06 and H9. This permits hydraulic fluid to flow from the spaces in the cylinders 32 and 34 beneath the pistons 28 and outwardly through the pipes III), through the valves I08, through the pipes I06, and thence through the valves I00 into the lines I02 to the reservoir 98.

' At the same time, the connections made between openings A and C of the valves I00 permit hydraulic fluid to flow from the reservoir 98 through the check valves 96, through the valves I00 and pipes I94 to the upper portions of the cylinders 32 and 34. It is seen, therefore, that the unit area pressure on both sides of the pistons 28 and 30 is the same. However, since the areas of the upper faces of these pistons are greater than the areas of their lower faces, the pistons will be urged downwardly. This force is also augmented by the weight of the slide I8, the dies, and the piston rods 24 and 26 together with their pistons 29 and 30. The result is that the slide I8 drops rapidly, its rate of descent being limited by the rate at which fluid can flow through the adjustable throttling valves I09 located in the pipes H0.

Just before the dies contact the work, a limit switch I49 is tripped to closed position by the slide I8. This limit switch is connected to line I 82 by conductor 208 and to the solenoid controlling valve 20I byconductor 2I2. The other side of the solenoid is connected to the line I84 through conductor 2 I8, conductor 204, switch I44, and conductor 246. When the solenoid is energized, switch 2I4 in a holding circuit is closed and the solenoid is connected to line I82 through switch 2I4, conductor 2I6, and conductor I88. Actuation of the valve 2I0 connects the clutch operating mechanism with the top of the reservoir 93, and the mechanism operates to engage the clutch 48, with the result that the flywheel 42 starts driving the cylinders 66 downwardly thereby forcing hydraulic fluid from these cylinders through the pipe I8 into the lines 92 and 94. The rise in pressure in the lines 92 and 94 immediately closes the check valves 96 and builds up a working pressure in the lines 92 and 94 which is communicated through the valves I and pipes I94 to the upper portions of the cylinders 32 and 34. The pistons 28 and 30 are therefore urged downwardly at great force by the hydraulic pressure produced in the cylinders 66. The slide therefore continues to. move downwardly, thereby drawing the metal to the desired shape.

At the end of the press stroke the pressure in the lines 92 and 94 rapidly builds up and opens one or the other or both of a pair of pressure switches I42 located in these lines. When either switch I42 is opened it breaks the circuit to the solenoid operated valve I62 which shifts to closed position and to vent the cylinder I58 to the atmosphere. The spring I63, pressing against the piston I56, shifts the spool I48 in the valve I99 to connect opening A to opening D and opening C to opening B. Both valves I00 operate together. Continued downward movement of the cylinders 68 therefore forces additional fluid under pressure through the valves I00, into the pipes I06, through the holding valves I08 and through the pipes H9 into the lower portions of the cylinders 32 and 34. At the same time the upper portions of these cylinders 32 and 34 are connected through the pipes I94 to the valves I00 and the pipes I92 to the reservoir 98. The result is that the pressure beneath the pistons 28 and 30 far exceeds that bearing against the upper faces of these pistons. Therefore the slide l8 moves upwardly so as to strip the dies.

As the slide [8 approaches the upper end of its stroke, it trips the limitswitch M4, which breaks the circuit to the solenoid controlling valves Zlt and I34. The valve 2H3 vents the clutch operating mechanism to the atmosphere to permit disengagement of the clutch 46, and the pipe I32 is vented to the atmosphere through the port I64 and vent duct I68 in the valve I34. The springs 124 therefore seat the valves H8 so as to prevent escape of fluid from the lower portions or the cylinders 32 and 34. The slide 18 therefore remains in its uppermost position. Simultanw ously disengagement of the clutch removes the drive from the cylinders 68, with the result that the pressure in the pipe 92 immediately drops to 200 pounds per square inch, the pressure in the reservoir 98, and closes the pressure operated switches I42 to condition the control circuit for another cycle. This pressure of 200 pounds per square inch acting within the cylinders 66, in the absence of any connection between the flywheel 42 and the shaft M, causes the cylinders 66 to move upwardly, thereby reversing the direction of rotation of the gear train and shaft at. This upward movement of the cylinders 66 continues until the cylinders have reached their uppermost positions, whereupon the cycle of the press. is completed.

The valves and I34 are shown only schematically andvthe valves H32 and 2 it may be similar to the valve I34. The actual construction and operation of such valves is well known and need not be set out in detail.

If it is assumed. that a press operating in the manner above described encounters an eccentric die load which throws the major portion of the load to one side of the slide 18, it is apparent that any tendency of the slide to tilt will immediately cause a drop in pressure in the upper portion of the cylinder 32 or 3d connected to the downwardly tilting side of the slide, since the two cylinders cylinders 66 which furnish the hydraulic pressure to the cylinders 3-2 and 34 travel downwardly together. In other words, the action is substantially the same. as that which takes place in a mechanical press in that one side. of the slide cannot be lower than the other and still receive power from the driving mechanism, whereas in a hydraulic press of ordinary construction the pressures in the two cylinders tendingto force. the slide downwardly remainvconstant regardless of the degree to which the slide tilts. It will. be seen further that by an appropriate setting of the two limit switches hit and M4 and the pressure switch 142, the point at which the slide begins its stroke, the point at which it ends its stroke, and the point at which the high working pressure is applied to the slide, all can be easily controlled so as to give the. slide any desired working stroke and any desired approach stroke within the maximum capacity of the press.

If a high coining pressure is desired, the pressure. switches I42 can be set to a comparatively high value so. that a high pressure will be produced by the dies before the direction of movement of the slideis reversed. On the other hand, if no substantial coining pressures are desired, the pressure switches I42 can be set to a low value.

From the above it will be seen that a metal working press embodying features of the present invention combines advantages of mechanical presses and hydraulicpresseswithout the import- 10 ant disadvantages commonly associated with either mechanical presses or hydraulic presses of conventional design.

Having thus described our invention, what we claim as new and useful and desire to secure by Letters Patent of the United States is:

1. In a punch press comprised of a frame, a slide reciprocable in the frame, and hydraulic cylinder and piston means for reciprocating said slide, a source of fluid under low pressure, means for connecting said low pressure source to said hydraulic cylinder and piston means so that pressure will be applied therefrom to operate said hydraulic cylinder and piston means to drive said slide during the initial phase of its downward stroke, a hydraulic pressure means for operating. said hydraulic cylinder and piston means under high pressure comprising a rotatable flywheel, means for rotating said flywheel, a rotatable shaft, clutch means for connecting said flywheel to said shaft, means driven from said shaft for compressing fluid and for passing the compressed fluid to said hydraulic cylinder and piston means during the work phase of the downi ward stroke of said slide, and means for connecting said low pressure source to said fluid compressing means to return it to initial position.

2. Hydraulic pressure producing apparatus to be incorporated in a hydraulic punch press, comprised of a frame, a slide reciprocable in the frame and a hydraulic cylinder and piston means for reciprocating said slide, said apparatus comprising a cylinder having a volumetric capacity su'liicient so that one compression stroke of said cylinder will deliver adequate hydraulic fluid to move said slide through a complete cycle, conduit means for connecting said cylinder to both ends of said hydraulic cylinder and piston means so that when fluid is delivered from said cylinder to said hydraulic cylinder and piston means at one end said. slide will be moved downwardly and when said fluid is delivered to said cylinder and piston means at the other end said slide will be moved upwardly, valve means in said conduit adapted to deliver hydraulic fluid first to the first mentioned end of said hydraulic cylinder and piston means and later to the other end of said hydraulic cylinder and piston means, a holding valve to prevent escape of fluid from the said second end of said hydraulic cylinder and piston means when said press is idle, a rotatable fly-- wheel, means for rotating said flywheel to store energy therein, rotatable driving means for operating said apparatus, and clutch means for connecting said flywheel to said rotatable driving means.

3. In a punch press, a frame, a slide reciprocable in the frame, cylinder and pistonmeansmfor reciprocating said slide; {single stroke pressure producing hydraulic cylinder, valve and conduit means for connecting said pressure producing cylinder to one end of the cylinder and piston means to move said slide downwardly or alternatively to the other end of said cylinder and piston means to move said slide upwardly, rotat-- able means for operating said pressure producing cylinder, a rotatable flywheel, means for rotating saidflywheel to store energy therein, clutch means for connecting said flywheel to said rotatable means for operating said cylinder, a reservoir for'storing hydraulic fluid, means for main-' taining said reservoir under a low pressure, and valve and conduit means connecting said reservoir to said pressure producing cylinder so that hydraulic fluid insaid reservoir under a low pres- 11 sure is adapted to return said pressure producing cylinder to its extended position.

4. A press comprising a frame, a slide reciprocable in the frame, hydraulic cylinder means for moving said slide downwardly when hydraulic fluid is forced into one end of said cylinder and to move said slide upwardly when hydraulic fluid is forced into the other end of said cylinder, a single stroke pressure producing cylinder adapted during each stroke in the pressure producing direction first to deliver hydraulic fluid to the first mentioned end of said cylinder and later to deliver hydraulic fluid to the other end of said hydraulic cylinder, control valve means for selectively connecting said pressure producing cylinder with either of the two opposite ends of said hydraulic cylinder, a rotatable flywheel, and drive means connecting said flywheel. to said pressure producing cylinder, said drive means including a clutch.

5. In a hydraulic press, a slide, a plurality of press cylinders connected to said slide, a plurality of pressure producing pumps of the positive displacement type, means connecting each of said pumps to one of said cylinders, drive means for driving all of said pumps, the last said means including mechanical means interconnecting the drives of all of said pumps so that the volumetric displacement of each of said pumps matches the volumetric displacement of others of the pumps regardless of the pressure on the discharge side of said pumps so that all of said cylinders operating on said slide will displace said slide uniformly regardless of the load distribution upon said slide, said drive means being connected to said pumps at the start of the work phase of the slide by means actuated by said slide during its downward stroke.

6. In a punch press, a slide, a plurality of press cylinders for displacing said slide, and means for operating said cylinders to displace said slide uniformly regardless of the load distribution upon said slide, the last said. means comprising a plurality of positive displacement piston and cylinder type pumps, conduit means connecting each of said pumps to one of said cylinders, each of said pumps being of large displacement so that a single stroke of each of said pumps will operate each of said cylinders through the work phase of the cycle and restore it to initial position, mechanical drive means interconnecting all of said pumps so as to drive all of said pumps at the same volumetric displacement rate, and means for imparting energy to said drive means.

7. The combination called for in claim 6, in

which the means for imparting energy includes a rotatable flywheel, means for rotating said flywheel, and clutch means for connecting said flywheel to said drive means.

8. The combination called for in claim 6, in which the drive means includes rack means associated with each of the reciprocable elements for rotating said pinions, a rotatable flywheel, means for rotating said flywheel, and clutch means for connecting said flywheel to said gear train means.

10. A punch press comprising a frame, a punch slide, hydraulic cylinder and piston means connected to said slide to actuate said slide in said frame, a source of fluid under low pressure for said cylinder and piston means, a source of fluid under high pressure for said cylinder and piston means; said high. pressure source comprising a reciprocable cylinder connected to said cylinder and piston means, a motor for driving said cyl inder to build up a pressure in said cylinder and piston means, and means for connecting said motor to said high pressure cylinder during the work phase of the stroke of said slide.

11. A punch press comprising a frame, a slide reciprocable in said frame, hydraulic cylinder and piston means for driving said slide, a source of fluid under relatively low pressure, conduit means connecting said low pressure source to said cylinder and piston means during the initial phase of the downstroke of said slide, a. source of fluid adapted to be subjected to relatively high pressure, and mean connecting said high pressure source to said cylinder and piston means during the work phase of the downward stroke of said slide and during the return movement of said slide to its initial position.

12. A punch press comprising a frame, a punch slide reciprocable in said frame, hydraulic cylinder and piston means connected to reciprocate said slide, a source of fluid under low pressure, conduit means connecting said low pressure source to said cylinder and piston means to efiect the initial phase of the downstroke of said slide, a source of fluid under high pressure, motor driven means for developing pressure in said high pressure source, conduit means connecting said high pressure source to said cylinder and piston means during the work phase of the downstroke of said slide, and pressure operated means to connect said high pressure source to said cylinder and piston means to restore said slide to its initial position.

13. A punch press comprising a frame, a punch slide, hydraulic cylinder and piston means for actuating said slide vertically in said frame, a source of fluid under relatively low pressure, means connecting said low pressure source to one end of said hydraulic cylinder and piston means to initiate downward movement of said slide, a reciprocable cylinder connected to said end of..said hydraulic cylinder and piston means,

motor means for reciprocating said cylinder to develop pressure therein, means for connecting said motor means to said reciprocable cylinder, said means being rendered effective by means actuated by said slide during its downward movement, and means actuated by means responsive to the pressure in said reciprocable cylinder to connect it to the opposite end of said hydraulic cylinder and piston means to restore the last said means to initial position.

14. The combination called for in claim 13 in which means connects said low pressure source to said second end of said hydraulic cylinder and piston means, and said means for connecting said motor means to said reciprocating cylinder is rendered ineffective, both said means being operated by means actuated by said slide as it is restored to its initial position.

HERBERT B. WERNER.

JOHN 'VERSON. 

